This invention relates to comminuting devices and more particularly to systems and processes for clearing a crusher of tramp material.
A crusher is a machine designed to reduce larger materials such as large rocks into smaller rocks, gravel, sand, and/or dust. Crushers may be used to reduce the size or change the form of waste materials. Crushing involves transferring forces amplified by mechanical advantage through robust crushing surfaces which are generally parallel or tangent to each other. Entering material is held between the crushing surfaces, and sufficient forces are applied to bring the crushing surfaces together. Energy is delivered to the material being crushed so that its molecules separate (i.e., fracture), or change alignment in relation to each other (i.e., deform).
Gyratory crushers can be used for primary or secondary crushing and generally comprise a conical head moveable with respect to a corresponding concave in close proximity. The surfaces of the head and concave are typically lined with manganese steel liners. The head moves slightly in a small circular motion via an eccentric arrangement, but does not rotate, whereas the concave remains stationary. Entering material falls between the head and concave and resides there while it is progressively crushed until its pieces are small enough to escape through a predetermined gap between the head and concave. The crushing action is caused by progressive opening and closing of the predetermined gap between the head and the concave.
Cone crushers, such as the one illustrated in FIG. 1 operate similarly to gyratory crushers, however, they generally comprise less steepness in the crushing chamber and more of a parallel zone between crushing surfaces 404, 504. Cone crusher 1 breaks up incoming entrance feed material 602 by squeezing it between a bowl 400 having a bowl liner 402 and a wear resistant mantle 502 supported by a head 500 mounted over top of a main shaft 700. The head 500 comprises a head bore 507 which receives an eccentric 900 spinning around main shaft 700 by virtue of a drive shaft 800 and one or more transmission members 802, 902 (e.g., bevel gears). The eccentric 900 comprises a bore 907 which accepts main shaft 700. Main shaft 700 is received by a shaft receiving portion 307 in a main frame hub 310. As the eccentric 900 rotates about the shaft 700, it causes the head 500 and mantle 502 to gyrate with respect to the bowl 400 and bowl liner 402. An axis 509 of the head bore 507 is generally offset from the axis 709 of the main shaft 700 as shown. One or more bushings (not shown) may be placed between the eccentric 900 and the head bore 507 and/or between the main shaft 700 and the eccentric bore 907. As the larger entrance material 602 enters the top of the cone crusher 1, it becomes wedged and squeezed between the mantle 502 and the bowl liner 402. Large pieces of ore are broken once, and then fall to a lower position within the crusher 1 as they become smaller in size. The ore is subsequently broken and the process continues until the comminuted material 604 is small enough to fall through a narrow predetermined gap “G” between the bottoms of the mantle 502 and the bowl liner 402.
When a crusher gets overloaded, it can jam, seize momentarily, or stall completely, leaving a large amount of material in the crushing chamber and hopper feeding the crushing chamber from above. To remove tramp iron or jammed material, the crushing chamber must be cleared of material. Some cone and gyratory crushers comprise hydraulic tramp release systems which serve to provide overload protection and minimize damage to the crusher when tramp passes through the crushing chamber. Such tramp release systems generally comprise two sets of hydraulic cylinders, as shown and described in U.S. Pat. No. 4,750,681. A first set of cylinders is activated to separate an upper crushing member from a lower crushing member and open the crushing chamber. This is generally called a clearing stroke. Another second set of cylinders serves to pull the upper crushing member towards the lower crushing member to close the crushing chamber so that crushing can take place. Having two sets of hydraulic cylinders adds to the cost, complexity, and failure mode of conventional crushers.
Moreover, as shown and described in U.S. Pat. No. 4,750,681 prior cylinders have been either directly attached by their body to main frames without means for angle compensation and with no piston rod attachment to the adjustment ring, or alternatively, have only been attached to adjustment rings by the piston rod with the cylinder body unattached to the main frame. Such arrangements lead to premature wear or failure, especially under high loads, because they may become cocked or unseated under high loads.